The Effect of a Host on the Primary Metabolic Profiling of Cuscuta Campestris’ Main Organs, Haustoria, Stem and Flower

Molecular Mechanism of Cuscuta Haustorium Specialization Inferences from Transcriptome and Metabolome Analysis

BACKGROUND

Cuscuta australis R. Br. is a parasitic herbaceous plant that obtains nutrients by forming specialized structures called haustoria to invade host plants.

METHODS

In this study, we elucidated the differences in the gene expression regulation and metabolic characteristics between Cuscuta australis and Glycine max (Glycine max (L.) Merr. Var Williams) through comprehensive transcriptomic and metabolomic analyses.

RESULTS

The results demonstrated significant differences in the gene expression and metabolic features between the haustorium and the distal stem segments. The differentially expressed genes absorbed by Cuscuta australis from the soybean host influence amino acid metabolism, and the expression of the S-adenosylmethionine decarboxylase gene may affect the production of 5'-methylthioadenosine. A high expression of the chalcone synthase enzyme could lead to an increased daidzein content. Many Glycine max genes were also integrated into Cuscuta australis within the haustorium.

CONCLUSIONS

This study systematically analyzed, for the first time, the significant differences in gene expression and metabolic characteristics between the haustoria and distal stem segments of Cuscuta. It also explored the nutrient absorption mechanisms of the host plant. Additionally, the research discovered that Cuscuta can absorb a substantial amount of host genes and adapt to its parasitic lifestyle through differential gene expression and metabolic changes. These findings provide important insights into the parasitic mechanisms of Cuscuta australis and lay the foundation for the development of effective control strategies.

Structural variety and pharmacological potential of naphthylisoquinoline alkaloids

Naphthylisoquinoline alkaloids are a fascinating class of natural biaryl compounds. They show characteristic mono- and dimeric scaffolds, with chiral axes and stereogenic centers. Since the appearance of the last comprehensive overview on these secondary plant metabolites in this series in 1995, the number of discovered representatives has tremendously increased to more than 280 examples known today. Many novel-type compounds have meanwhile been discovered, among them naphthylisoquinoline-related follow-up products like e.g., the first seco-type (i.e., ring-opened) and ring-contracted analogues. As highlighted in this review, the knowledge on the broad structural chemodiversity of naphthylisoquinoline alkaloids has been decisively driven forward by extensive phytochemical studies on the metabolite pattern of Ancistrocladus abbreviatus from Coastal West Africa, which is a particularly "creative" plant. These investigations furnished a considerable number of more than 80-mostly new-natural products from this single species, with promising antiplasmodial activities and with pronounced cytotoxic effects against human leukemia, pancreatic, cervical, and breast cancer cells. Another unique feature of naphthylisoquinoline alkaloids is their unprecedented biosynthetic origin from polyketidic precursors and not, as usual for isoquinoline alkaloids, from aromatic amino acids-a striking example of biosynthetic convergence in nature. Furthermore, remarkable botanical results are presented on the natural producers of naphthylisoquinoline alkaloids, the paleotropical Dioncophyllaceae and Ancistrocladaceae lianas, including first investigations on the chemoecological role of these plant metabolites and their storage and accumulation in particular plant organs.

The Effect of 10 Crop Plants That Served as Hosts on the Primary Metabolic Profile of the Parasitic Plant Phelipanche aegyptiaca

Phelipanche aegyptiaca Pers. is a holoparasitic plant that parasitizes various types of host plants. Its penetration into host roots causes a massive reduction in the yield of many crop plants worldwide. The nature of the compounds taken by the parasite from its host is still under debate in the scientific literature. To gain more knowledge about the effect of the hosts on the parasite's primary metabolic profile, GC-MS analyses were conducted on the parasites that developed on 10 hosts from four plant families. There are three hosts from each family: Brassicaceae, Apiaceae and Solanaceae and one host from Fabaceae. The results showed significant differences in the metabolic profiles of P. aegyptiaca collected from the different hosts, indicating that the parasites rely strongly on the host's metabolites. Generally, we found that the parasites that developed on Brassicaceae and Fabaceae accumulated more amino acids than those developed on Apiaceae and Solanaceae that accumulated more sugars and organic acids. The contents of amino acids correlated positively with the total soluble proteins. However, the aromatic amino acid, tyrosine, correlated negatively with the accumulation of the total phenolic compounds. This study contributes to our knowledge of the metabolic relationship between host and parasite.

Metabolic changes induced by Cuscuta campestris Yunck in the host species Artemisia campestris subsp. variabilis (Ten.) Greuter as a strategy for successful parasitisation

C. campestris parasitisation increases internal host defences at the expense of environmentally directed ones in the host species A. campestris, thus limiting plant defence against progressive parasitisation. Cuscuta campestris Yunck is a holoparasitic species that parasitises wild species and crops. Among their hosts, Artemisia campestris subsp. variabilis (Ten.) Greuter is significantly affected in natural ecosystems. Limited information is available on the host recognition mechanism and there are no data on the interactions between these species and the effects on the primary and specialised metabolism in response to parasitisation. The research aims at evaluating the effect of host-parasite interactions, through a GC-MS untargeted metabolomic analysis, chlorophyll a fluorescence, ionomic and δ¹³C measurements, as well as volatile organic compound (VOC) fingerprint in A. campestris leaves collected in natural environment. C. campestris parasitisation altered plant water status, forcing stomatal opening, stimulating plant transpiration, and inducing physical damages to the host antenna complex, thus reducing the efficiency of its photosynthetic machinery. Untargeted-metabolomics analysis highlighted that the parasitisation significantly perturbed the amino acids and sugar metabolism, inducing an increase in the production of osmoprotectants, which generally accumulate in plants as a protective strategy against oxidative stress. Notably, VOCs analysis highlighted a reduction in sesquiterpenoids and an increase in monoterpenoids levels; involved in plant defence and host recognition, respectively. Moreover, C. campestris induced in the host a reduction in 3-hexenyl-acetate, a metabolite with known repellent activity against Cuscuta spp. We offer evidences that C. campestris parasitisation increases internal host defences via primary metabolites at the expense of more effective defensive compounds (secondary metabolites), thus limiting A. campestris defence against progressive parasitisation.